Narrative:

While returning from a commercial pilot training flight, we obtained a final WX observation from hhr tower just as the tower was closing daily operations. The special observation was 400 ft indefinite ceiling and 2 mi visibility. Frequently, the coastal marine layer does not extend past the harbor freeway, which is approximately 2 mi east of the approach end of runway 25 at hhr airport. We decided to overfly hhr airport at 1500 ft to try to determine the extent of the cloud cover and the visibility conditions. We were able to follow el segundo blvd and see the airport through breaks in the marine layer. We returned to just north of compton airport which was clear. Compton airport is about 4 mi east of hhr airport. We then let down to 1100-1200 ft and from there we could see the approach lights, runway lights, rotating beacon and strobe lights of runway 25 at hawthorne. Because of this, we decided to continue a VFR approach into hawthorne airport. We let down to 500-600 ft and tracked south of the localizer inbound until we intercepted the VASI and safely landed at hhr. We were never able to determine the exact base of the clouds, but we estimated that they were 400-500 ft above us at all times while on GS and that the visibility was at least 3 mi. The visibility and cloud base conditions at hhr are frequently much better in the approach direction (east) than in the takeoff direction when a marine layer occurs. Hawthorne converts to an uncontrolled airport (not a control zone) when the tower closes at XA00 each day. Far 91.155 says that when operating VFR at night in uncontrolled airspace below 1200 ft, a pilot is required to have 3 SM visibility and 500 ft clearance below the cloud ceiling. The one thing that is not indicated is how a WX observation is obtained under these conditions and whether the pilot has the authority/authorized to make his own WX observation and proceed on that basis. At night it is very difficult and dangerous for the pilot to try to determine the exact cloud base. For day operations, far 91.155 only requires a pilot to have 1 SM visibility and remain clear of the clouds. Therefore, it seems to be a safe operation, when landing at night at an uncontrolled airport with the runway environment always in sight, that the pilot only be required to remain clear of the clouds as long as there is 1 mi visibility. Certainly, in our case, we were not in a hazardous situation, and while we may have stretched the letter of far 91.155, we were able to conduct a safe flight operation.

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Original NASA ASRS Text

Title: SMA ON TRAINING FLT ENCOUNTERS LOWERING WX CONDITIONS ON APCH TO LNDG.

Narrative: WHILE RETURNING FROM A COMMERCIAL PLT TRAINING FLT, WE OBTAINED A FINAL WX OBSERVATION FROM HHR TWR JUST AS THE TWR WAS CLOSING DAILY OPS. THE SPECIAL OBSERVATION WAS 400 FT INDEFINITE CEILING AND 2 MI VISIBILITY. FREQUENTLY, THE COASTAL MARINE LAYER DOES NOT EXTEND PAST THE HARBOR FREEWAY, WHICH IS APPROX 2 MI E OF THE APCH END OF RWY 25 AT HHR ARPT. WE DECIDED TO OVERFLY HHR ARPT AT 1500 FT TO TRY TO DETERMINE THE EXTENT OF THE CLOUD COVER AND THE VISIBILITY CONDITIONS. WE WERE ABLE TO FOLLOW EL SEGUNDO BLVD AND SEE THE ARPT THROUGH BREAKS IN THE MARINE LAYER. WE RETURNED TO JUST N OF COMPTON ARPT WHICH WAS CLR. COMPTON ARPT IS ABOUT 4 MI E OF HHR ARPT. WE THEN LET DOWN TO 1100-1200 FT AND FROM THERE WE COULD SEE THE APCH LIGHTS, RWY LIGHTS, ROTATING BEACON AND STROBE LIGHTS OF RWY 25 AT HAWTHORNE. BECAUSE OF THIS, WE DECIDED TO CONTINUE A VFR APCH INTO HAWTHORNE ARPT. WE LET DOWN TO 500-600 FT AND TRACKED S OF THE LOC INBOUND UNTIL WE INTERCEPTED THE VASI AND SAFELY LANDED AT HHR. WE WERE NEVER ABLE TO DETERMINE THE EXACT BASE OF THE CLOUDS, BUT WE ESTIMATED THAT THEY WERE 400-500 FT ABOVE US AT ALL TIMES WHILE ON GS AND THAT THE VISIBILITY WAS AT LEAST 3 MI. THE VISIBILITY AND CLOUD BASE CONDITIONS AT HHR ARE FREQUENTLY MUCH BETTER IN THE APCH DIRECTION (E) THAN IN THE TKOF DIRECTION WHEN A MARINE LAYER OCCURS. HAWTHORNE CONVERTS TO AN UNCTLED ARPT (NOT A CTL ZONE) WHEN THE TWR CLOSES AT XA00 EACH DAY. FAR 91.155 SAYS THAT WHEN OPERATING VFR AT NIGHT IN UNCTLED AIRSPACE BELOW 1200 FT, A PLT IS REQUIRED TO HAVE 3 SM VISIBILITY AND 500 FT CLRNC BELOW THE CLOUD CEILING. THE ONE THING THAT IS NOT INDICATED IS HOW A WX OBSERVATION IS OBTAINED UNDER THESE CONDITIONS AND WHETHER THE PLT HAS THE AUTH TO MAKE HIS OWN WX OBSERVATION AND PROCEED ON THAT BASIS. AT NIGHT IT IS VERY DIFFICULT AND DANGEROUS FOR THE PLT TO TRY TO DETERMINE THE EXACT CLOUD BASE. FOR DAY OPS, FAR 91.155 ONLY REQUIRES A PLT TO HAVE 1 SM VISIBILITY AND REMAIN CLR OF THE CLOUDS. THEREFORE, IT SEEMS TO BE A SAFE OP, WHEN LNDG AT NIGHT AT AN UNCTLED ARPT WITH THE RWY ENVIRONMENT ALWAYS IN SIGHT, THAT THE PLT ONLY BE REQUIRED TO REMAIN CLR OF THE CLOUDS AS LONG AS THERE IS 1 MI VISIBILITY. CERTAINLY, IN OUR CASE, WE WERE NOT IN A HAZARDOUS SIT, AND WHILE WE MAY HAVE STRETCHED THE LETTER OF FAR 91.155, WE WERE ABLE TO CONDUCT A SAFE FLT OP.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.